1. Field of the Invention
The present invention relates to a mobile radio station such as a GSM (Global System for Mobile communication) mobile phone, and particularly to a radio base station monitoring control by the mobile radio station.
2. Description of the Related Art
In the GSM system, each radio base station reserves four TDMA frames every n multiframes as a paging channel. The value of n can be set for a particular radio base station to any value from 2 to 9. A single block of paging channel frames are long enough for the mobile radio station to listen to its current radio base station for any incoming call and to receive from two neighboring radio base stations in each frame and measure the signal strengths thereof. Thus the signal strength received from eight neighboring radio base stations can be monitored in every n multi-frame.
If two monitor operations are performed in every paging channel TDMA frame a considerable amount of power will be wasted, if the mobile radio station is, for example, at the center of a cell where it is unlikely that any hand-off to a neighboring radio base station will be required imminently.
On the other hand, although it is simple to arrange that fewer monitor operations are performed, this will have the effect of degrading cell reselection performance.